• The Journal of Engineering Geology
• /
• v.3 no.3
• /
• pp.279-293
• /
• 1993

In recent yeaes, the collapses of man made structures have been encountered from time to time due to the deformation of the ground in korea. Furthermore, the possibilities of casasters from the ground deformation suCh as landslide and active fault are atrracting our attention to the deformation monitoring. In this study, two-coordinate tilt which was monitored during six months in order to develop tediniques for prevention of disasters from the ground deformation. The two-coordinate tilt which was detected by a tilt-sensor installed in shallow depth on the slope with the sensitivity of 0.0001 arc.sec in every 10 minutes was recorded continously to PC through the interface with 200-m line coonection. The observed digital tilt data. together with the relevant meteorological data were analyzed in reference to engineering application. During the whole observation period of six months, the net tilt is 10.06 arc.sec to the west and 73.88 arc.sec to the south. Consequently the ground has a tilt of 74.56 arc.sec to the direction of $S7.75^{\circ}W$ with average tilting of 0.02 arc.sec/hour. In spite of such fast and large tilting, it is interpreted in view of engineering aspects that the site is much safe from danger, since both East-West and North-South components of tilt converge as time goes by. Two categories of deformational events are recognized ; one is toward the direction of surface slope and the other is to the direction of increased pore pressure. Tiks are acenain to have a close relation with precipitation of rain. The daily variation of two-coordinate tilt is delayed 4.3 hours in average after the variation of atmospheric temperature. A certain correlation between atmospheric pressure and deformation might be revealed.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.3 no.4
• /
• pp.1-10
• /
• 2000

Satellite remote sensing images have much more information compared to a paper map. But these images are generally handled as particular image format gained from optical sensor, and must be processed and analyzed by computer with high priced digital image processing system. For the extraction of digital elevation model(DEM) from satellite image, we used the overlay image by SPOT-3 of Chuncheon area at the Kangwon province. According to the image condition, the precious geometric correction, the bundle adjustment for ortho-image generation and the stereo image mapping by several technical approaches were processed. So that we developed the methods of automatic DEM extraction and efficient stereo image map generation which can improve the digital image processing steps. Also, we applied the multiple direction birdeye view image for modeling and analysis using the remotely sensed overlay images with high resolution.

• Korean Journal of Remote Sensing
• /
• v.35 no.6_4
• /
• pp.1313-1318
• /
• 2019

The Korea Aerospace Research Institute (KARI) has developed and operated a total of three KOMPSAT series(K-3, 3A and 5). The main purpose of satellite development is to utilize data obtained from satellites. In other words, continuous efforts should be made to improve the accuracy of data processing and expand the application areas. This special issue introduces pre-processing and application technologies based on optic and Synthetic Aperture Radar (SAR) sensors of KOMPSAT series. It is believed that more systematic research and development will be needed as follow-up KOMPSAT series and small satellites are under development.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.444-444
• /
• 2023

하천 및 저수지와 같은 공간의 수체 탐지는 수자원 관리에서 매우 중요하며, 유역의 수문학적 과정을 이해하는데 도움을 준다. 수문학적 데이터 수집은 우량계, 수위계와 같은 물리적 인프라의 배치가 필요하다. 그러나 상대적으로 저개발된 국가는 수문학적 측정을 위한 인프라가 매우 미흡한 것이 현실이며, 북한과 같은 비접근 지역에 대한 수문학적 과정을 분석하는데는 한계가 있다. 인공위성 원격탐사 센서 중 SAR영상은 지표면에 직접 전파를 방사하고 산란되어 돌아오는 신호를 수신하여 영상을 만들기 때문에 일반적인 광학영상과는 달리 햇빛의 유무와 강우, 구름여부 등의 기상 조건의 영향을 거의 받지 않는 장점이 있다. 또한 국내와 같이 계절적인 요인과 인간활동에 의해 변화되는 물 순환을 SAR 영상은 지표수의 계절적 및 연간 변동성을 모니터링하는데 매우 유용한 자료로 평가되고 있다. 본 연구는 SAR영상을 이용하여 국내의 검증 가능한 지역의 저수지 수면적 변화를 모니터링하고 저수지 수면적과 저수량 분석을 수행하는 것을 목적으로 하였다. 분석자료인 SAR영상은 ESA의 Sentinel-1영상을 2022년 4월부터 2022년 11월의 자료를 수집하여 소양강댐 저수지 수면적과 저수량과의 관계식을 도출하였다. 수체 추출을 위한 SAR 영상은 특히 수로의 일부 가장자리와 홍수터의 식물 존재로 인한 제외지의 매핑에 부정확성을 포함하여 처리에 몇 가지 단점을 갖는 한계도 존재하지만 악천후의 기상 조건에서도 작동할 수 있는 SAR 영상의 능력 덕분에 규칙적인 시간 간격으로 수체면적의 변화에 대한 정보를 제공할 수 있다. 향후 북한 지역의 주요 댐 저수지 수면적에 대한 연간변화와 장기간의 추세를 분석하는 연구를 진행할 계획이다.

• KIPS Transactions on Software and Data Engineering
• /
• v.8 no.4
• /
• pp.145-152
• /
• 2019

Unlike a single value from a sensor device, a massive data set has characteristics for various processing aspects; input data may be formed in a different format, the size of input data varies, and the processing time of analyzing input data is not predictable. Therefore, context aware systems may contain complex modules, and these modules can be implemented and used in different ways. In order to solve these problems, we propose a method to handle context information from the result of analyzing massive data. The proposed method considers analysis work as a different type of abstracting context and suggests the way of representing context information. In experiment, we demonstrate how the context processing engine works properly in a couple of steps with healthcare services.

• Korean Journal of Remote Sensing
• /
• v.35 no.6_4
• /
• pp.1327-1339
• /
• 2019

Surface reflectance obtained by absolute atmospheric correction from satellite images is useful for scientific land applications and analysis ready data (ARD). For Landsat and Sentinel-2 images, many types of radiometric processing methods have been developed, and these images are supported by most commercial and open-source software. However, in the case of KOMPSAT 3/3A images, there are currently no tools or open source resources for obtaining the reflectance at the top-of-atmosphere (TOA) and top-of-canopy (TOC). In this study, the atmospheric correction module of KOMPSAT 3/3A images is newly implemented to the optical calibration algorithm supported in the Orfeo ToolBox (OTB), a remote sensing open-source tool. This module contains the sensor model and spectral response data of KOMPSAT 3A. Aerosol measurement properties, such as AERONET data, can be used to generate TOC reflectance image. Using this module, an experiment was conducted, and the reflection products for TOA and TOC with and without AERONET data were obtained. This approach can be used for building the ARD database for surface reflection by absolute atmospheric correction derived from KOMPSAT 3/3A satellite images.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.6
• /
• pp.643-648
• /
• 2013

In this paper, we developed a system which can detect and can alarm about the sailing provocative climate by using a photo. The research on domestic shipbuilding industry and in IT fusion technology is under construction, but a reliable safety device which can alarm a sailor about the circumstances of the fog and rain during ship operation as soon as possible due to the constant state in domestic. In this paper, a compact, for system low-power transceiver and data processing equipment for sensing were developed, also a performance evaluation got accomplished with simulation analysis. In results, it is operating normally at least 32.36[dB] and maximum values f 89.20[dB] in the domestic, and 32.55 to 60.66[dB] in the outdoors.

• Journal of Astronomy and Space Sciences
• /
• v.26 no.4
• /
• pp.499-510
• /
• 2009

In this paper, relative orbit of Low Earth Orbit satellites is determined using only GPS measurements and the effects of Equatorial Spread-F (ESF), that is one of biggest ionospheric irregularities, are investigated. First, relative orbit determiation process is constructed based on doubly differenced GPS observations. In order to see orbit determination performance, relative orbit of two GRACE satellites is estimated for one month in 2004 when no ESF is observed. The root mean square of the achieved baselines compared with that from K-Band Ranger sensor is about 2~3 mm and average of 95% of ambiguities are resolved. Based on this performance, the relative orbit is estimated for two weeks of two difference years, 2003 when there are lots of ESF occurred, and 2004 when only few ESF occurred. For 2003, the averaged baseline error over two weeks is about 15 mm. That is about 4 times larger than the case of 2004 (3.6 mm). Ionospheric status achieved from K-Band Ranging sensor also shows that more Equatorial Spread-F occurred at 2003 than 2004. Investigation on raw observations and screening process revealed that the ionospheric irregualarities caused by Equatorial Spread-F gave significant effects on GPS signal like signal loss or enhancement ionospheric error, From this study, relative orbit determination using GPS observations should consider the effect of Equatorial Spread-F and adjust orbit determination strategy, especially at the time of solar maximum.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.162-162
• /
• 2011

표면파 속도 측정은 근래 토목분야에서는 비파괴 지반조사기법으로 활용되고 있다. 최근에는 디지털 신호처리기술의 발달과 함께, 더욱 정확해진 자료분석 알고리즘을 통하여 표면파 탐사관련 기술이 향상되어 3차원의 공간연속적인 시험이 가능해졌다. 본 연구는 표면파의 분산 특성을 이용하여 콘크리트 구조물의 깊이별 강성평가를 하는 SASW(Spectral Analysis of Surface Waves)기법과 STFT(Short time Fourier Transform)과 HWT(Harmonic Wavelet Transform)를 이용한 주파수영역에서의 공진주파수를 통한 부재평가 기법인 IE(Impact Echo)기법을 이용하여 대상부재의 강도평가를 수행하기 위한 시제품 개발을 수행하였다. 시제품은 메인프레임과 2개의 센서로 이루어져 측정을 수행하며 측정장치와 DAQ장치 및 S/W로 구성되어 있다. 메인프레임의 진동특성영향을 제거하기 위하여 2개의 센서는 프레임과 띄움구조로 설계하였고 센싱하는 위치는 대상 재료의 밀착되어 계측할 수 있도록 설계하였다. 탄성파를 계측하여 대상 재료의 깊이별 측정된 표면파의 속도를 계측하며 개발된 시제품의 구조물별 적용성 평가를 위한 실험을 수행하였고 평균 표면파 속도를 통해 추정한 콘크리트 두께와 결함 및 강도 추정의 적용성을 평가하였다. 시제품을 이용해 시험콘크리트 표면파를 측정한 결과 SASW기법을 이용하여 깊이에 대한 위상속도 분포와 IE기법의 결과로 개발된 시제품의 합리적 적용성이 평가되었다. 그러나 재료의 강도추정에 있어서는 각각 알고리즘의 주파수분석 요소들에 의해 변동되는 경향을 보여 추후 많은 테스트를 통해 속도-강도 추정의 회귀곡선식을 S/W에 탑재시키고 다양한 방법으로 조합하는 알고리즘으로 신뢰성있는 강도추정을 위한 알고리즘을 개발하여야 한다.

• Journal of Korean Society for Geospatial Information Science
• /
• v.18 no.2
• /
• pp.3-12
• /
• 2010

In previous studies, the digital measurement systems and analysis algorithms were developed by using the related techniques, such as the aerial photograph detection and high resolution satellite image process. However, these studies were limited in 2-dimensional geo-processing. Therefore, it is necessary to apply the 3-dimensional spatial information and coordinate system for higher accuracy in recognizing and locating of geo-features. The objective of this study was to develop a stochastic algorithm for the optimal sensor placement using the 3-dimensional spatial analysis method. The 3-dimensional information of the LiDAR was applied in the sensor field algorithm based on 2- and/or 3-dimensional gridded points. This study was conducted with three case studies using the optimal sensor placement algorithms; the first case was based on 2-dimensional space without obstacles(2D-non obstacles), the second case was based on 2-dimensional space with obstacles(2D-obstacles), and lastly, the third case was based on 3-dimensional space with obstacles(3D-obstacles). Finally, this study suggested the methodology for the optimal sensor placement - especially, for ground-settled sensors - using the LiDAR data, and it showed the possibility of algorithm application in the information collection using sensors.